The Reason for the Need to toggle between Caller-IDs is simple, and should be obvious from my Text:
When I call someone in the U.S., I display my U.S. Caller-ID, and when I call someone in Australia, I would like to display my Australian Caller-ID. This makes it easier for the Call Recipient to call me back.
Think about it: if You lived in the U.S., would You want to call someone back in Australia (or vice versa) ?
This could be very costly for international Calling Rates, and may not be possible at all (depending on the Mobile or Landline Service Provider) !
Would You even answer the Call from a non-U.S. Number ?
If I wanted to "send unwanted phone calls to people" as You insinuated, I would simply block my Caller-ID.
Yours is not a very nice Response, an Insult, and certainly not helpful !!!